1. Field of the Invention
The present invention is directed to controlling access to digital data, and more particularly, to a system for providing secure communication of information to recipient devices in a manner such that the information can only be communicated or accessed at specified locations.
2. Description of Related Art
Rapid advances in computer, telecommunications and networking technology have enabled new opportunities and applications that were impossible just a few years ago. These advances are exemplified by the rapid growth of network systems seeking to deliver “high-value” content securely to authorized recipients. Examples of such networks include those that handle confidential, sensitive, or classified information in the health care, financial, and national security fields. They also include networks that handle intellectual property or copyrighted data such as computer software, literary works, and entertainment products. A fundamental aspect of these networks is the sharing of information between users, nodes and components of the network. But, whenever information is shared there is also the risk that the information will be obtained by unauthorized persons. Controlling the security of the information in such systems, including confidentiality, authenticity, integrity, authorized use, transaction secrecy, site protection, etc., has therefore proven to be a critical aspect of such networks.
One technology that is commonly used to protect information on these networks is cryptography. Cryptography is the use of codes and ciphers to protect data from unintended disclosure or modification. It is primarily used to control access to communications transmitted over open networks, but may also be used to control access to stored data. In a transmission utilizing cryptography to protect digital data, the sender converts the original data, or “plaintext,” into a coded equivalent called “ciphertext” using an encryption algorithm. The ciphertext is then decoded (or decrypted) by the receiver and thereby turned back into plaintext. The encryption algorithm uses a key, which in digital systems is a string of bits. In general, the larger the number of bits in the key, the longer it takes to break the code using so-called “brute force” methods.
A drawback of conventional cryptographic systems is the inherent risk in distributing keys to recipients of encrypted information. If an unauthorized user intercepts the keys, then that unauthorized user could gain access to the encrypted information. Within military systems, a portable hardware device known as a loader or fill device is often used to transfer confidential information, such as encryption/decryption keys and other mission critical information. The loader/fill device typically includes an electronic memory in which the confidential information may be stored. The loader can be electrically or optically connected directly to a recipient device, such as a satellite receiver, in order to load the confidential information directly into the recipient device. The use of a direct electrical or optical connection between the loader and the recipient device, such as via a cable or shielded connector, precludes radio frequency (RF) broadcasts that can be intercepted. The security of the communication network therefore depends on the physical control over the loader. If the loader were to be misplaced or misappropriated, then the security of the entire communication network could be compromised.
Co-pending patent application Ser. No. 09/992,378, filed Nov. 16, 2001, for SYSTEM AND METHOD FOR DELIVERING ENCRYPTED INFORMATION IN A COMMUNICATION NETWORK USING LOCATION IDENTITY AND KEY TABLES, discloses a system for controlling access to data based not only on a secret key, but also on location. For example, in the context of digital cinema, such a system would enable a producer of digital movies to be assured that its products could only be decrypted in certain theaters whose locations are known in advance. Or, a provider of entertainment products such as movies and subscription television would be assured that its products could only be decrypted within the premises of its customers or within a particular geographic region. This capability would guard against many threats, including the unauthorized distribution of copyright-protected works over the Internet or through other means. Even if the keys were compromised, recipients would not be at the proper location to enable decryption.
Accordingly, it would be desirable to provide a system for providing secure communication of information to recipient devices in a manner such that the information can only be communicated or accessed at specified locations. It would also be desirable to provide a system to protect a device containing critical information, such as encryption/decryption keys, and that would render the critical information unusable to unauthorized persons if the device were misappropriated.